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718112a8fe
Currently none of these is being used, but eventually they will, once more code gets ported over. So it's better to have them right away and avoid editing the project file too much, only to revert that later.
145 lines
3.6 KiB
C++
145 lines
3.6 KiB
C++
// Nes_Snd_Emu 0.1.8. http://www.slack.net/~ant/
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#include "Nes_Namco_Apu.h"
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/* Copyright (C) 2003-2006 Shay Green. This module is free software; you
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can redistribute it and/or modify it under the terms of the GNU Lesser
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General Public License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version. This
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module is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
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details. You should have received a copy of the GNU Lesser General Public
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License along with this module; if not, write to the Free Software Foundation,
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Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */
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#include "blargg_source.h"
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Nes_Namco_Apu::Nes_Namco_Apu()
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{
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output( NULL );
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volume( 1.0 );
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reset();
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}
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void Nes_Namco_Apu::reset()
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{
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last_time = 0;
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addr_reg = 0;
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int i;
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for ( i = 0; i < reg_count; i++ )
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reg [i] = 0;
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for ( i = 0; i < osc_count; i++ )
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{
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Namco_Osc& osc = oscs [i];
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osc.delay = 0;
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osc.last_amp = 0;
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osc.wave_pos = 0;
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}
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}
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void Nes_Namco_Apu::output( Blip_Buffer* buf )
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{
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for ( int i = 0; i < osc_count; i++ )
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osc_output( i, buf );
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}
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/*
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void Nes_Namco_Apu::reflect_state( Tagged_Data& data )
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{
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reflect_int16( data, BLARGG_4CHAR('A','D','D','R'), &addr_reg );
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static const char hex [17] = "0123456789ABCDEF";
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int i;
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for ( i = 0; i < reg_count; i++ )
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reflect_int16( data, 'RG\0\0' + hex [i >> 4] * 0x100 + hex [i & 15], ® [i] );
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for ( i = 0; i < osc_count; i++ )
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{
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reflect_int32( data, BLARGG_4CHAR('D','L','Y','0') + i, &oscs [i].delay );
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reflect_int16( data, BLARGG_4CHAR('P','O','S','0') + i, &oscs [i].wave_pos );
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}
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}
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*/
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void Nes_Namco_Apu::end_frame( blip_time_t time )
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{
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if ( time > last_time )
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run_until( time );
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assert( last_time >= time );
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last_time -= time;
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}
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void Nes_Namco_Apu::run_until( blip_time_t nes_end_time )
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{
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int active_oscs = (reg [0x7F] >> 4 & 7) + 1;
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for ( int i = osc_count - active_oscs; i < osc_count; i++ )
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{
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Namco_Osc& osc = oscs [i];
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Blip_Buffer* output = osc.output;
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if ( !output )
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continue;
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output->set_modified();
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blip_resampled_time_t time =
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output->resampled_time( last_time ) + osc.delay;
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blip_resampled_time_t end_time = output->resampled_time( nes_end_time );
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osc.delay = 0;
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if ( time < end_time )
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{
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const uint8_t* osc_reg = ® [i * 8 + 0x40];
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if ( !(osc_reg [4] & 0xE0) )
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continue;
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int volume = osc_reg [7] & 15;
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if ( !volume )
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continue;
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blargg_long freq = (osc_reg [4] & 3) * 0x10000 + osc_reg [2] * 0x100L + osc_reg [0];
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if ( freq < 64 * active_oscs )
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continue; // prevent low frequencies from excessively delaying freq changes
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blip_resampled_time_t period =
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output->resampled_duration( 983040 ) / freq * active_oscs;
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int wave_size = 32 - (osc_reg [4] >> 2 & 7) * 4;
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if ( !wave_size )
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continue;
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int last_amp = osc.last_amp;
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int wave_pos = osc.wave_pos;
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do
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{
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// read wave sample
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int addr = wave_pos + osc_reg [6];
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int sample = reg [addr >> 1] >> (addr << 2 & 4);
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wave_pos++;
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sample = (sample & 15) * volume;
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// output impulse if amplitude changed
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int delta = sample - last_amp;
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if ( delta )
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{
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last_amp = sample;
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synth.offset_resampled( time, delta, output );
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}
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// next sample
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time += period;
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if ( wave_pos >= wave_size )
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wave_pos = 0;
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}
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while ( time < end_time );
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osc.wave_pos = wave_pos;
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osc.last_amp = last_amp;
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}
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osc.delay = time - end_time;
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}
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last_time = nes_end_time;
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}
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